Hi Mario,

Here are a few suggestions

1) Fail fast in this case:

this annotation has no effect if the corresponding pattern's type hasn't been annotated with @PropSpecific

Fail Fast with an exception like this:
throw new IllegalStateException("The factClass (" + factClass + ") has a property (" + property + ") that has a @Modifies annotation, but the class isn't annotated with @PropSpecific.");
If for a later version, we receive user input that there is actually a good case where @Modifies exists without @PropSpecific, we can always allow it (vica versa is not possible).

2) @Modifies( "firstName, lastName" ) should not put the comma (,) inside the quotes. Go for:
@Modifies( "firstName", "lastName" )
or @ModifiesCombination( @Modifies("firstName"), @Modifies("lastName") )
The last way might look a bit strange, but it's a common practice, for example in JPA-hibernate:
http://docs.jboss.org/hibernate/core/4.0/javadocs/org/hibernate/annotations/ColumnTransformers.html
http://docs.jboss.org/hibernate/core/4.0/javadocs/org/hibernate/annotations/ColumnTransformer.html
That last way won't break when there are additional properties on the @Modifies annotations (while the other approaches will):
@ModifiesCombination( @Modifies("firstName", whenImplementsInterface = FirstNameable.class), @Modifies("lastName", whenImplementsInterface = LastNameable.class) )

3) What's the point of doing a @PropSpecific on a field instead of a class?

declare Person
@propSpecific
firstName : String

4) I also believe we should stick to Java naming conventions [1] as close as possible because the main target audience to start using our drools jars is the java programmers audience.
The stranger our stuff looks to them, the more likely they 'll try to write "a simple solution" themselves instead of using our "complex" framework.
4a) Like Edson says: start with a capital like all other annotations.

* I think we should keep the property names consistent between the java and the declare element, so I suggest you use uppercase for both (@PropSpecific).

4b) The naming conventions also state not to abbreviate to fast, so I 'd prefer @PropertySpecific over @PropSpecific

[1] Oracle's Java coding conventions, which are the base for JBoss's coding conventions:
http://www.oracle.com/technetwork/java/codeconv-138413.html

Op 17-01-12 20:20, Mario Fusco schreef:

Hi all,

just a quick recap of what I did until now to check if we are all on the same page and also agree with the naming convention I used.

The property specific feature is off by default in order to make the behavior of the rule engine backward compatible with the former releases. If you want to activate it on a specific bean you have to annotate it with @propSpecific. This annotation works both on drl type declarations:

declare Person
    @propSpecific
    firstName : String
    lastName : String
end

and on Java classes:

@PropSpecific
public static class Person {
    private String firstName;
    private String lastName;
}

Moreover on Java classes you can also annotate any method to say that its invocation actually modifies other properties. For instance in the former Person class you could have a method like:

@Modifies( "firstName, lastName" )
public void setName(String name) {
    String[] names = name.split("\\s");
    this.firstName = names[0];
    this.lastName = names[1];
}

That means that if a rule has a RHS like the following:

modify($person) { setName("Mario Fusco") }

it will correctly recognize that both the firstName and lastName have been modified and act accordingly. Of course the @Modifies annotation on a method has no effect if the declaring class isn't annotated with @PropSpecific.

The third annotation I have introduced is on patterns and allows you to modify the inferred set of properties "listened" by it. So, for example, you can annotate a pattern in the LHS of a rule like:

Person( firstName == $expectedFirstName ) @watch( lastName ) // --> listens for changes on both firstName (inferred) and lastName
Person( firstName == $expectedFirstName ) @watch( * ) // --> listens for all the properties of the Person bean
Person( firstName == $expectedFirstName ) @watch( lastName, !firstName ) // --> listens for changes on lastName and explicitly exclude firstName
Person( firstName == $expectedFirstName ) @watch( *, !age ) // --> listens for changes on all the properties except the age one

Once again this annotation has no effect if the corresponding pattern's type hasn't been annotated with @PropSpecific.

I've almost finished with the development of this feature (at the moment I am missing the compile-time check of the properties named in the @watch annotation together with some more exhaustive tests), so if you think that I misunderstood something or there is room for any improvement (or you just don't like the annotation's names I chose) please let me know as soon as possible.

Mario
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-- 
With kind regards,
Geoffrey De Smet